Method for removing hydrocarbon contaminants from solid materials

ABSTRACT

A system for removing hydrocarbons from solid materials. Contaminated solids are combined with a solvent (preferably terpene based) to produce a mixture. The mixture is washed with water to generate a purified solid product (which is removed from the system) and a drainage product. The drainage product is separated into a first fraction (consisting mostly of contaminated solvent) and a second fraction (containing solids and water). The first fraction is separated into a third fraction (consisting mostly of contaminated solvent) and a fourth fraction (containing residual solids and water). The fourth fraction is combined with the second fraction to produce a sludge which is separated into a fifth fraction (containing water which is ultimately reused) and a sixth fraction (containing solids). The third fraction is then separated into a seventh fraction (consisting of recovered solvent which is ultimately reused) and an eighth fraction (containing hydrocarbon waste).

CONTRACTUAL ORIGIN OF THE INVENTION

The United States Government has rights in this invention pursuant toContract No. DE-AC07-76ID01570 between the U.S. Department of Energy andEG&G Idaho, Inc.

BACKGROUND OF THE INVENTION

The present invention generally relates to the decontamination of solidmaterials, and more particularly to the treatment of contaminated soil,gravel, sand, and other solid compositions in order to removehydrocarbon contaminants therefrom.

Increased demand for petroleum and chemical products has resulted in thedevelopment of extensive and widespread production facilities. In thepetroleum industry, exploration and production facilities are oftendeveloped on a large scale in remote areas. Many regions in which theproduction of petroleum and chemical products occur are environmentallysensitive. The discharge of organic hydrocarbons and related by-productscan therefore create an adverse environmental impact, especially withrespect to the contamination of soil, silt, clay, sand, gravel, and thelike. For example, the contamination of soil with petroleum products(e.g. oil, refined fuels, and similar materials) presents significantcontainment and decontamination problems. One problem of particularconcern involves the need to treat substantial amounts of contaminatedmaterials (e.g. soil) in a rapid and effective manner while avoiding theuse of other, potentially harmful chemical agents.

Many attempts have been made to treat large volumes of contaminatedsolid materials (e.g. soil contaminated with oils and other petroleumproducts). For example, prior methods involved the incineration ofcontaminated materials, as well as the burial thereof. These methodseither produce additional contaminants (e.g. air pollution in the caseof incineration) or result in long-term disposal problems when thecontaminated solids are buried. A need therefore remains for aremediation/decontamination system which is able to treat large amountsof solid materials to remove hydrocarbon contaminants therefrom. It isimportant that the selected treatment process be capable of producingtreated materials which may be released into the environment withoutadverse consequences. It is also important that the selected treatmentprocess accomplish the foregoing goals without using environmentallyharmful chemical agents. The present invention as described hereinsatisfies these goals and enables the removal of hydrocarboncontaminants from solid materials in an environmentally conscious mannerwhile avoiding the problems described above. Accordingly, the inventionrepresents an advance in the art of waste treatment and environmentalremediation as discussed in detail below.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a treatment systemfor the removal of chemical contaminants from solid materials in a rapidand effective manner.

It is another object of the invention to provide a treatment system forsolid materials which is especially useful in the removal of hydrocarboncontaminants from soil compositions (e.g. dirt, sand, gravel, silt,clay, and the like)

It is another object of the invention to provide a treatment system forremoving hydrocarbon contaminants from solid materials (e.g. soilcompositions) which is readily implemented on a large scale.

It is further object of the invention to provide a treatment system forremoving hydrocarbon contaminants from solid materials which involvesthe use of environmentally compatible, natural product-based solvents.

It is a further object of the invention to provide a treatment systemfor removing hydrocarbon contaminants from solid materials which isreadily applicable to a wide variety of hydrocarbon contaminants andsolid materials, and is likewise characterized by a high degree ofmobility.

It is a still further object of the invention to provide a treatmentsystem for removing hydrocarbon contaminants from solid materials whichavoids the production of secondary pollutants during the treatmentprocess.

It is a still further object of the invention to provide a treatmentsystem for removing hydrocarbon contaminants from solid materialswherein the decontaminated solid materials may be released into theenvironment without adverse consequences.

It is an even further object of the invention to provide a treatmentsystem for removing hydrocarbon contaminants from solid materialswherein a substantially closed-loop system is used in which treatmentagents are actively purified and reused.

In accordance with the foregoing objects, the present invention involvesa unique and highly efficient system for removing hydrocarboncontaminants from solid materials. The term "hydrocarbon contaminant" asused herein shall encompass a wide variety of organic materialsincluding but not limited to waste oils, processed fossil fuels, crudeoils, petroleum fractions derived from crude oil (petroleumby-products), and organic pesticides. Other materials which may beremoved specifically include (1) benzene, toluene, ethylbenzene, andxylene compounds; (2) halogenated solvents; (3) chlorinated biphenyls;as well as other organic compositions which are soluble within theselected solvent materials described below. Accordingly, the presentinvention shall not be limited with respect to the foregoing classes oforganic contaminants which are provided for example purposes.

The term "solid material" as used herein may likewise encompass a widevariety of materials including but not limited to soil compositions(e.g. dirt, gravel, sand, slit, and/or clay), as well as other solidswhich are substantially insoluble in the selected solvents describedherein. In this regard, the present invention shall not be limited tothe foregoing solid materials which are again provided for examplepurposes.

To remove hydrocarbon contaminants from the selected solid materials,the present invention involves a substantially "closedloop" system inwhich chemical solvents, processing water, and the like are purified andreused in the system when needed, thereby reducing material costs andenvironmental impact. To generally accomplish treatment in accordancewith the invention (which will be described in detail in the followingsection entitled "Detailed Description of Preferred Embodiments"), solidmaterials mixed with hydrocarbon contaminants are first combined with aselected solvent in a containment vessel. While the present inventionshall not be limited to any particular solvent, the use of one or moreterpene compositions is preferred. Terpenes are best known as primarycomponents of essential oils, and are considered to be natural products.They specifically originate as complex mixtures of flavors andfragrances in higher plants. From a chemical standpoint, terpenesconsist of unsaturated organic compounds having the empirical chemicalformula C₁₀ H₁₆. They are further classified as monocyclic (e.g.dipentene), dicyclic (e.g. pinene), or acyclic (e.g. myrcene). Furtherinformation regarding terpene compositions will be provided below.Terpenes are preferred for use in the present invention since they areenvironmentally biocompatible. Exemplary terpene compositions suitablefor use in the invention include but are not limited to alpha-pinene,beta-pinene, limonene, terpinolene, alpha-terpinene, gamma-terpinene,beta-phellandrene, paracymene, 1,4-cineole, 1,8-cineole, and mixturesthereof.

The selected terpene solvent and solid material are combined to form amixture in which the hydrocarbon contaminant composition is solvated(e.g. dissolved) within the terpene composition. The treated mixture isthereafter washed with water. While the present invention shall not belimited to any particular washing method or system, a preferredembodiment involves placement of mixture within a washing chamber havinga first section with at least one primary screen member therein and asecond section with at least one secondary screen member therein. Withinthe washing chamber, the second section is optimally positioneddownstream from the first section. The treated mixture is initiallymoved from the containment vessel onto the primary screen member in thefirst section of the washing chamber. Thereafter, a supply of washingwater is applied to the mixture on the primary screen member in order toproduce a drainage product which passes through the primary screenmember and a purified solid product which remains on the primary screenmember and does not pass therethrough. The drainage product consists of(1) the washing water; (2) the solvent having the hydrocarboncontaminant composition dissolved therein; and (3) finely-dividedportions of the solid material small enough to pass through the primaryscreen member. In contrast, the purified solid product consists ofremaining portions of the solid material large enough to prevent passagethrough the primary screen member.

At this point, in the preferred embodiment described herein, thepurified solid product is transferred to the secondary screen member inthe second section of the washing chamber. In the second section of thewashing chamber, a supply of rinse water is applied to the purifiedsolid product on the secondary screen member, with the rinse waterpassing therethrough. The use of rinse water in this mannersubstantially "polishes" the purified solid product. The rinse waterwhich passes through the secondary screen member includes only minimalamounts of fine solid materials and organic compositions sincesubstantially all of these components were removed in the first sectionof the washing chamber. As a result, the rinse water (after passagethrough the secondary screen member) can be transferred to the firstsection of the washing chamber for use in the washing of additionalamounts of solid material which subsequently enter the treatment system.

The final step in the washing process involves removal of the purifiedsolid product from the treatment system (e.g. washing chamber) after theapplication of rinse water as described above. The purified solidproduct is substantially free from the hydrocarbon contaminantcomposition, and may thereafter be released into the environment withoutadverse consequences. At this point, it should be noted that thepurified solid product is not sterile and may be used as a suitablehabitat and/or biological substrate for added microbial populations,soil builders, microbial nutrients, and native plant seeds as desired.

As noted above, the present invention shall not be limited to anyparticular type of washing system or components. Modifications of theforegoing process are possible. For example, while the use of a dualstage washing/rinsing process is preferred and produces highly efficientresults, the present invention may be modified to involve a single stagewashing process depending on site-specific parameters and the extent ofcontamination. Regarding the type of equipment which can be used inconnection with the foregoing process, many different systems may beemployed. For example, a preferred system involves a containment vesselhaving an auger-type feed mechanism which delivers the treated mixtureto a cylindrical, axially-rotating washing chamber. The washing chamberpreferably includes an interior region therein surrounded by a sidewall. Fixedly secured to the inner surface of the side wall is acontinuous, upwardly-extending arrangement of helical flights (e.g. ahelical flight assembly) having a plurality of evenly-placed bafflemembers secured to the inner surface of the side wall between theflights. These components enable the efficient mixing and continuousmovement of the mixture within the washing chamber during rotation ofthe chamber. If this type of chamber is used, it may likewise include afirst section and a second section downstream from the first section.The first section will preferably have a primary screen member thereinconsisting of an annular section of screening material which forms theside wall of the washing chamber within the first section. The secondsection of the washing chamber will preferably have the same generalconfiguration as the first section. Specifically, the second sectionwill include a secondary screen member consisting of an annular sectionof screening material which forms the side wall of the washing chamberwithin the second section.

Positioned within the cylindrical washing chamber are a plurality ofconduits each having multiple spray nozzles thereon. A first conduit ispositioned upstream from the first section of the washing chamber and isdesigned to deliver additional solvents (e.g. terpene materials) to themixture as it moves through the chamber. The use of additional solventsis optional and will depend on site-specific considerations involvingthe type and quantity of contaminants to be removed. A second conduit ispositioned within the first section of the washing chamber and isdesigned to spray washing water onto the mixture as it moves through thefirst section and passes over the primary screen member. To collect thedrainage product which passes through the primary screen member, acollecting tank is located outside of the washing chamber and beneaththe first section. Finally, a third conduit is positioned within thesecond section of the washing chamber and is designed to spray rinsewater onto the purified solid product as it moves through the secondsection and passes over the secondary screen member. To collect therinse water which passes through the secondary screen member, anadditional collecting tank is located outside of the washing chamber andbeneath the second section.

Once again, the present invention shall not be limited to the foregoingtreatment apparatus. Other units having different structural designs andcomponents may likewise be used for the purposes described herein.

In accordance with the closed-loop characteristics of present invention,the remaining process steps involve treatment of the drainage productand the separation of components therefrom. As discussed below, thesecomponents may be reused in other parts of the process, therebyimproving operational efficiency and minimizing environmental impact.Specifically, the drainage product (which includes aqueous components,organic components and finely-divided solid materials) is initiallyseparated into a first fraction (which is predominantly organic incharacter) and a second fraction (which is predominantly aqueous).Separation may be accomplished using numerous methods including but notlimited to centrifugation or cyclonic separation. In a preferredembodiment, a first cyclonic separator unit in fluid communication withthe washing chamber is provided. The drainage product is thereafterintroduced into the first cyclonic separator unit at a fluid pressuresufficient to cause the drainage product to rapidly swirl therein. Rapidswirling of the drainage product causes it to separate into the firstand second fractions listed above. The first fraction consists of thesolvent (e.g. the selected terpene composition) having the hydrocarboncontaminant composition dissolved therein, and the second fractionconsists of the washing water and finely-divided portions of solidmaterial which passed through the primary screen member. The first andsecond fractions are thereafter removed from the first cyclonicseparator unit. The second fraction is then routed to a storage tank forsubsequent treatment as described below.

In a preferred embodiment, the first fraction (which is primarilyorganic in character) is treated to remove any further (e.g. residual)aqueous and solid components therefrom. This may be accomplished using anumber of methods including centrifugation or cyclonic separation.Preferably, a second cyclonic separator unit substantially identical tothe first cyclonic separator unit is provided. The second cyclonicseparator unit is in fluid communication with and downstream from thefirst cyclonic separator unit. The first fraction is introduced into thesecond cyclonic separator unit at a fluid pressure sufficient to causethe first fraction to rapidly swirl therein. Swirling of the firstfraction in this manner causes it to separate into a third fraction anda fourth fraction. The third fraction consists of the solvent (e.g. theselected terpene material) with the hydrocarbon contaminant compositiondissolved therein, and the fourth fraction consists of any residualwater and residual solid material which remained in the first fractionafter separation of the drainage product into the first and secondfractions. The third and fourth fractions are then removed from thesecond cyclonic separator unit. The fourth fraction is combined with thesecond fraction in the storage tank to produce a sludge product.

The sludge product is thereafter treated to separate the water thereinfrom the remaining solid materials. In a preferred embodiment, this isaccomplished by a centrifuge unit in fluid communication with anddownstream from the first and second cyclonic separator units. Thesludge product is introduced into the centrifuge unit and rotated at arotational speed sufficient to separate the sludge product into a fifthfraction and a sixth fraction. The fifth fraction consists of washingwater from the second fraction and residual water from the fourthfraction which combine to produce a supply of recycled water. The sixthfraction contains finely-divided portions of solid material from thesecond fraction and residual solid material from the fourth fraction.The fifth and sixth fractions are then removed from the centrifuge unit.The sixth fraction is thereafter disposed of or released into theenvironment as desired (which should not cause problems sincesubstantially all of the hydrocarbon contaminant composition has beenremoved therefrom).

Next, the third fraction is treated in order to remove the hydrocarboncontaminant composition from the solvent (e.g. the selected terpenematerial). This may be accomplished using a number of conventionalprocessing methods, although fractional distillation is preferred.Specifically, a conventional fractional distillation unit is providedwhich is in fluid communication with the second cyclonic separator unit.The third fraction is thereafter introduced into the fractionaldistillation unit, followed by heating of the third fraction in anamount sufficient to fractionally distill and generate a seventhfraction and an eighth fraction from the third fraction. The seventhfraction consists of remaining (e.g. recovered) quantities of thesolvent, and the eighth fraction consists of the hydrocarbon contaminantcomposition. The seventh and eighth fractions are then removed from thefractional distillation unit.

The remaining (e.g. recovered) quantities of terpene solvent from theseventh fraction are thereafter supplied to the initial containmentvessel for reuse in the treatment of additional solid materials whichenter the treatment system. The reuse of solvents in this manner notonly provides a maximum degree of economy, but reduces any storage ordisposal problems which may exist regarding the solvent.

Likewise, the supply of recycled water from the fifth fraction istransferred to the washing chamber (e.g. the second section) of thetreatment system, where it is reused as rinse water in connection withadditional amounts of solid material which enter the system.

Finally, a number of options exist with respect to the recoveredhydrocarbon contaminant composition (e.g. the eighth fraction). Thehydrocarbon contaminant composition may be stored or disposed of in aconventional manner, depending on the chemical nature of thecomposition. In a preferred embodiment, if a petroleum based compositionis involved (e.g. crude oil, fuel products, or derivatives thereof), thecomposition may be combusted or burned as an energy source for thegeneration of heat, electrical power, and the like. Specifically, thetreatment system described herein may include a conventional generatorsystem having an internal combustion engine associated therewith. Therecovered hydrocarbon contaminant composition would then be supplied tothe generator system for use as fuel (alone or in combination with otherfuel materials) to generate electricity. In this type of system, it maybe necessary to provide a filtering step between the fractionaldistillation unit and generator system in which the hydrocarboncomposition would be passed through a conventional filter unit to removeextraneous solid matter. The extraneous solid matter would then berouted into the initial containment vessel of the treatment system fordecontamination as described above.

Finally, the foregoing generator system could include an optional heatexchanger unit designed to pre-heat the third fraction before it entersthe fractional distillation unit. Pre-heating of the third fractionwould reduce the energy requirements of the fractional distillationunit, thereby improving the energy efficiency of the entire treatmentsystem.

The present invention represents an advanced system for removinghydrocarbon contaminants from solid materials. In accordance with theclosed-loop nature of the system, it enables the recycling of water andsolvents to achieve a maximum degree of operating efficiency. These andother objects, features, and advantages of the invention shall bedescribed below in the following Brief Description of the Drawings andDetailed Description of Preferred Embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a detailed, schematic illustration showing the process stepsand components associated with a preferred embodiment of the presentinvention.

FIG. 2 is a schematic flow diagram corresponding to the embodiment ofFIG. 1 which illustrates the multiple separation steps which occurduring the treatment process.

FIG. 3 is a schematic, cross-sectional illustration of an exemplarycontainment vessel and washing chamber suitable for use in theembodiment of FIG. 1.

FIG. 4 is a detailed, schematic illustration showing the process stepsand components associated with an alternative embodiment of theinvention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The present invention involves a unique and highly efficient method forthe decontamination and restoration of solid material s combined withhydrocarbon contaminants. It offers particular utility in the chemicaland petroleum industries wherein decontamination on a large scale may benecessary. As stated above, the term "hydrocarbon contaminant" usedherein shall encompass a wide variety of hydrocarbon and organicmaterials including but not limited to waste oils, processed fossilfuels, crude oils, petroleum fractions derived from crude oil (petroleumby-products), and organic pesticides. Other materials which may beremoved specifically include (1) benzene, toluene, ethylbenzene, andxylene compounds; (2) halogenated solvents; (3) chlorinated biphenyls,as well as other organic compositions which are soluble within theselected solvent materials described below. Accordingly, the inventionshall not be limited to any particular classes or groups of hydrocarbonmaterials, and is prospectively applicable to a wide variety of organiccompositions. The term "solid material" may likewise encompass variousmaterials including but not limited to soil compositions (whichtypically involve dirt, gravel, sand, silt, and/or clay), as well asother solids which are substantially insoluble in the selected solventmaterials. However, the present invention shall not be limited totreatment of the foregoing materials which are again provided forexample purposes.

The technology associated with the present invention is based onnumerous physical and chemical treatment processes combined in a uniquemanner. These processes include biochemical solvation, liquid/liquidextraction, liquid/solid extraction, material size classification,mechanical/hydraulic scrubbing, and phase separation of organic andaqueous fractions in a chemical mixture. These techniques cooperativelyproduce a multi-step process which is able to decontaminate a widevariety of solid materials in a rapid and efficient manner.

To illustrate the process of the present invention, a schematic flowdiagram is provided in FIG. 1. While FIG. 1 represents a preferredembodiment, the invention shall not be specifically limited to the stepsand information provided below. Instead, the invention may be modifiedin accordance with site-specific considerations as necessary andappropriate. With reference to FIG. 1, a schematic representation of anexemplary processing/treatment system is generally designated atreference number 10. The system 10 includes a treatment unit 12 having acontainment vessel 14 in the form of a hopper 16. As illustrated in FIG.1, the containment vessel 14 is initially provided with a supply ofsolid material 18. The solid material 18 is combined with at least onehydrocarbon contaminant composition. In a preferred embodiment, thesolid material 18 is physically manipulated so that any large portionsthereof are reduced in size to an easily handled form. The system 10 iscapable of treating solid materials generally having individual portions(e.g. particles or chunks) with diameters ranging from about 0.025-60mm. Size control may be accomplished prior to introduction of the solidmaterial 18 into the containment vessel 14 using conventional means(e.g. standard mechanical grinding/pulverizing systems). Alternatively,size control may be undertaken within the containment vessel 14 using anumber of conventional mechanical systems which simultaneously functionto transfer the solid material 18 from the containment vessel 14 tosubsequent parts of the processing system 10. An exemplary mechanicalsystem for accomplishing these goals would include a motor-driven feedauger 20 illustrated schematically in FIG. 1. In addition, thecontainment vessel 14 may also include a plurality of optional,motor-driven counter-rotating disks 21 which provide additionalmechanical forces sufficient to break up large portions of the solidmaterial 18. It should be noted that all of the physical structures usedin the processing system 10 (including but not limited to thecontainment vessel 14 and associated components) should be constructedof a metal (e.g. stainless steel) or other material which is notchemically affected by the solvent being used for decontamination.

Within the containment vessel 14, the solid material 18 is combined witha supply of a solvent 22 designed to remove the foregoing hydrocarboncontaminant composition from the solid material 18. Specifically,contact between the solvent 22 and the contaminated solid material 18will cause solvation (e.g. dissolution) of the hydrocarbon compositioninto the solvent 22. While the present invention shall not be limited toany particular solvent, the use of one or more terpene compositions ispreferred. Terpene compositions are best known as primary components ofessential oils, and are therefore classified as natural products. Theyare oligomers of isoprene and originate as complex mixtures of flavorsand fragrances in higher plants. From a chemical standpoint, terpenesbasically involve unsaturated organic compounds having the empiricalchemical formula C₁₀ H₁₆. These compounds occur in most essential oilsand oleo-resins derived from plants, and many exist in the form ofalcohols, esters, ethers, ketones, and aldehydes. They are furtherclassified as monocyclic (e.g. dipentene), dicyclic (e.g. pinene), oracyclic (e.g. myrcene). They are commercially available on an industrialscale and can be purchased in volumes typically ranging from about5-2000 gallons. Many high purity terpenes are used by the food,beverage, and cosmetic industries as fragrance and flavoring compounds.Terpene compositions are preferred solvent materials in the presentinvention because they are environmentally biocompatible. Exemplaryterpenes suitable for use as solvent 22 include but are not limited tothe following materials and mixtures thereof: ##STR1##

In particular, 1,4-cineole and 1,8-cineole are classified as terpeneethers which co-elute with terpene hydrocarbons during isolation. All ofthe foregoing terpene compositions are commercially available from anumber of sources including but not limited to the Bush, Boake, andAllen Company (a division of Union Camp Corporation) of Jacksonville,Fla. (U.S.A.).

The amount of solvent 22 to be combined with the solid material 18 inthe containment vessel 14 may be varied, depending on the extent ofcontamination and the type of hydrocarbon contaminant being removed. Formost purposes, it is preferred that the solvent 22 (e.g. the terpenecomposition) be added to the solid material 18 in a solvent: solidmaterial weight ratio of about 1:1 to 6:1. Also, while pre-heating ofthe solvent 22 is not normally required, pre-heating may enhanceseparation efficiency in isolated cases determined by preliminary pilotstudies on the solid materials being processed. If pre-heating isundertaken, the solvent 22 will normally be heated to a temperaturewithin about 5° C. above the cloud point of the specific solvent beingused.

Depending on site-specific considerations, optional separationenhancement agents 24 may be added to the containment vessel 14 incombination with the solid material 18 and solvent 22. These agents 24typically include various salts (e.g. CaCl₂ or NaCl) as well as pHcontrol agents including but not limited to HC1 or NaOH. The agents 24are collectively designed to improve the wettability characteristics ofthe solid material 18 to create enhanced separation efficiency. As notedabove, addition of the agents 24 is optional, depending on site specificconsiderations, as well as preliminary pilot studies on the solidmaterials 18 being treated. If one or more separation enhancement agents24 are used, the amounts thereof to be combined with the solid material18 are variable, again depending on numerous factors determined bypreliminary pilot tests.

Once the solid material 18, solvent 22, and any optional separationenhancement agents 24 are combined within the containment vessel 14,they form a mixture 26 which is transferred by the feed auger 20 (orother conventional conveying system) into a washing chamber 30schematically illustrated in FIG. 1. Transfer of the mixture 26 from thecontainment vessel 14 to the washing chamber 30 is typically undertakenin a rapid manner since residence time of the mixture 26 in thecontainment vessel 14 is minimal. In a preferred embodiment, the mixture26 will typically reside within the containment vessel 14 for a periodof about 3-10 minutes before being transferred to the washing chamber30. It should also be noted that, immediately upon entry of the mixture26 into the washing chamber 30, an optional supply of supplementalsolvent 33 (preferably of the same type as solvent 22) may be applied tothe mixture 26 at position 34 within the washing chamber 30 if desired.Application of the supplemental solvent 33, as well as the amount ofsolvent 33 to be applied will depend on a variety of extrinsic factorsincluding but not limited to the type of solid material 18 beingtreated, as well as the hydrocarbon contaminant composition beingremoved. Preliminary pilot tests may be used to determine whether theapplication of supplemental solvent 33 will be necessary.

In a preferred embodiment, the washing chamber 30 will include at leastone and preferably two screen members therein which are used tofacilitate treatment of the solid material 18. In the embodiment of FIG.1, the washing chamber 30 will include a first section 36 having aprimary screen member 38 therein. The primary screen member 38 istypically constructed of conventional metal (e.g. stainless steel)screening material having a preferred mesh size of not less than about0.1 micron. The term "screen member" as used herein shall also encompassmetal plate members or other comparable structures (not shown) having aplurality of perforations or openings therethrough. The mixture 26 isplaced directly on the primary screen member 38, followed by theintroduction of a supply of washing water 40 thereto. With reference toFIG. 1, the washing water 40 is initially stored within a containmenttank 42 of conventional design. When delivery is desired, the washingwater 40 passes through line 44 and into pump 48. The washing water thenpasses through line 50 which terminates above the primary screen member38 within the first section 36 of chamber 30. The pump 48 (as well asthe other pumps described below) are of conventional design. Standarddisk flow pumps, screw pumps, centrifugal pumps and the like may be usedin connection with all of the pump units discussed herein. In addition,a unique aspect of the processing system 10 is the origin of the washingwater 40 as discussed in greater detail below.

In a preferred embodiment, the washing water 40 will be applied at apressure level of about 50-200 psi, although the selected pressure mayvary, depending on the size and configuration of the processing system10. The amount of washing water 40 to be applied will also vary in viewof numerous factors including but not limited to the size and capacityof the processing system 10, as well as the nature of the solid material18 and hydrocarbon contaminant. In most cases, the application of about1-4 gallons of washing water 40 per pound of mixture 26 will besufficient.

As the washing water 40 moves downwardly through the mixture 26, itphysically washes the solvent 22 (and dissolved hydrocarbon contaminant)from the mixture 26. In addition, as the washing water 40 passes throughthe mixture 26, it draws finely-divided portions of the solid material18 therewith. All of these materials (in combination) pass through theprimary screen member 38 and collect within a containment tank 52positioned outside of the washing chamber 30 and beneath the primaryscreen member 38 as illustrated in FIG. 1. Accordingly, a drainageproduct 54 (FIG. 3) is generated which resides within the containmenttank 52. The drainage product 54 includes (1) the washing water 40; (2)the solvent 22 having the hydrocarbon contaminant composition dissolvedtherein; and (3) finely-divided portions of the solid material 18 smallenough to pass through the primary screen member 38 (which is used forsize classification purposes). The drainage product 54 is thereafterrouted from the containment tank 52 through line 60 where it is pumpedby pump 62 (e.g. of the same type as pump 48) into line 64. The drainageproduct 54 is subsequently processed to remove useful componentstherefrom as described below. The material which remains on the primaryscreen member 38 will consist of a purified solid product 68 illustratedin FIG. 1. The purified solid product 68 is comprised of remainingportions of the solid material 18 large enough to prevent the passage ofsuch portions through the primary screen member 38. At this stage, thepurified solid product 68 has nearly all of the hydrocarbon contaminantcomposition removed therefrom, and is considered to be effectivelydecontaminated at this stage. However, in a preferred embodiment, thepurified solid product 68 is rinsed with an additional supply of waterin order to remove any residual materials and effectively "polish" theproduct 68. To accomplish this step, the purified solid product 68 istransferred to a second section 69 of the washing chamber 30 whichincludes a secondary screen member 70 therein. As shown in FIG. 1, thesecond section 69 is positioned downstream from the first section 36.The secondary screen member 70 is preferably of the same type andconfiguration as the primary screen member 38. In an alternativeembodiment, the secondary screen member 70 may include a mesh size whichis different from the primary screen member 38 if further sizeclassification is desired.

After the purified solid product 68 is transferred to the secondaryscreen member 70, it is rinsed with a supply of rinse water 72. Theultimate origin of the rinse water 72 is a unique aspect of the presentinvention, and will be described in detail below. After the rinse water72 passes through the purified solid product 68 and secondary screenmember 70, it is collected within the containment tank 42 describedabove. As shown in FIG. 1, the containment tank 42 is positioned outsideof the washing chamber 30 and beneath the secondary screen member 70.Because of the substantially clean character of the rinse water 72within the tank 42, and in order to conserve water, the rinse water 72may be transferred to the first section 36 of the washing chamber 30 foruse as the washing water 40. Specifically, the rinse water 72 (after itpasses through the secondary screen member 70) may be used as the supplyof washing water 40 in connection with solid materials on the primaryscreen member 38. To accomplish this process, the collected water withinthe containment tank 42 (hereinafter characterized as the washing water40) passes through line 44, pump 48, and line 50 into the first section36 of the washing chamber 30 as described above. To ensure an adequatesupply of washing water 40, any additional water which may be needed inthe system 10 (due to evaporation, spillage, etc.) may be supplied tothe containment tank 42 from a supply of feedstock water 82 which isconnected to the containment tank 42 via line 84.

At this point, the purification process is completed, and the finalsolid product 86 (FIGS. 1 and 3) is removed from the washing chamber 30.In accordance with the present invention, the final solid product 86will have not less than about 98% of the hydrocarbon contaminantcomposition removed therefrom. At this level, the product 86 may bereturned to the environment under most circumstances without adverseconsequences (especially if soil materials are involved). It should benoted that the final solid product 86 is not sterile in view of thebiologically compatible solvents involved, and may be used as a suitablehabitat and/or biological substrate for added microbial populations,soil builders, microbial nutrients, and native plant seeds as desired.Furthermore, depending on the size characteristics of the washingchamber 30 and associated components, as well as the type of materialsbeing treated, the system 10 is capable of treating at least about 20yd³ /hr. of contaminated solid material 18. Accordingly, the system 10has the capacity to treat large quantities of contaminated materials ina highly effective manner.

As previously indicated, the processing system 10 shall not be limitedto the specific containment vessel 14, washing chamber 30, andassociated components described above and schematically illustrated inFIG. 1. For example, a number of different devices may be used toinitially treat/decontaminate the solid material 18. An exemplary andpreferred treatment apparatus 100 suitable for this purpose isschematically illustrated (partially in cross-section) in FIG. 2. Withreference to FIG. 2, the apparatus 100 specifically includes acontainment chamber 102 which is manufactured from a metal (e.g.stainless steel) that is inert with respect to the solvent being used.While the capacity of the chamber 102 may be varied depending onsite-specific conditions including the amount of contaminated solidmaterial to be treated, an optimum and preferred capacity will be about100-500 lbs. The chamber 102 (shown cross-sectionally in FIG. 2) has apartially open top portion 104, a bottom wall 106, a front wall 108, anda rear wall 110. The chamber 102 also has an interior region 112designed to receive solid material 18 therein. Located within theinterior region 112 and spaced inwardly from the rear wall 110 is aninternal wall 114 shown schematically in FIG. 2. Positioned between therear wall 110 and the internal wall 114 is an open zone 116, thefunction of which will be described below. The internal wall 114 extendsdownwardly from the top portion 104 as illustrated and terminates abovethe bottom wall 106 to form a gap 120 therebetween. Also positionedwithin the interior region 112 of the chamber 102 is a downwardly-angledwall 122 which forms an acute angle "X" of about 45° relative to thebottom wall 106. The downwardly-angled wall 122 has an outer end 124 andan inner end 126, with the inner end 126 abuttingly engaging the bottomwall 106 (FIG. 2). In addition, the inner end 126 is positioned directlyahead of and spaced apart from the gap 120 as shown.

Positioned within the open zone 116 between the rear wall 110 andinternal wall 114 is a vertical screw-type feed auger 130 ofconventional design which extends continuously from the bottom wall 106to the top portion 104 of the chamber 102. The feed auger 130 includes acentral shaft 132 having a continuous helical flight assembly 134secured thereto. The feed auger 130 further includes a lower end 138which spans the gap 120 between the internal wall 114 and bottom wall106 as shown in FIG. 2. In addition, the feed auger 130 includes anupper end 140 which is operatively connected to a standard electricmotor 142. The entire feed auger 130 is sized so that it may freelyrotate within the open zone 116 and not frictionally engage the rearwall 110 and internal wall 114.

Finally, the interior region 112 of the chamber 102 includes a tubularfeed conduit 146 partially positioned therein, with the conduit 146having a first end 148 and a second end 150. The term "tubular" as usedherein shall generally signify an elongate structure having a bore orpassageway therethrough surrounded by a continuous wall. The first end148 of the conduit 146 is connected to the supply of solvent 22 asdescribed above. The second end 150 of the conduit 146 is closed so thatfluid will not pass therethrough. Positioned between the first end 148and the second end 150 is a plurality of spray nozzles 152 ofconventional design. The spray nozzles 152 are used to deliver solvent22 from the conduit 146 to solid material 18 within the interior region112 of the chamber 102. The number of spray nozzles 152 may be varieddepending on the desired capacity of the system with which it is used.In a preferred embodiment, about 15-30 spray nozzles 152 may beemployed.

With continued reference to FIG. 2, the rear wall 110 of the chamber 102includes an opening 154 therein which is adjacent the upper end 140 ofthe feed auger 130. The opening 154 includes an elongate chute 160 whichextends outwardly from the rear wall 110. The chute 160 is preferablymanufactured from the same material (e.g. stainless steel) used toproduce the containment chamber 102. The chute 160 leads into a washingchamber 164 which performs the same functions listed above in connectionwith the washing chamber 30. In the embodiment of FIG. 2, the washingchamber 164 includes a tubular (e.g. substantially cylindrical) housing166 having an open first end 168, an open second end 170, a continuousannular side wall 172, and an interior region 174 surrounded by the sidewall 172. The housing 166 and associated components are preferablymanufactured of the same materials used to produce the containmentchamber 102 (e.g. stainless steel), and are shown cross-sectionally inFIG. 2.

Fixedly secured to the inner surface 176 of the side wall 172 andextending outwardly into the interior region 174 is a continuous helicalflight assembly 180 which includes a plurality of integrally-connectedflight members 182. The flight members 182 are secured by welding or thelike to the inner surface 176 of the side wall 172 as schematicallyillustrated in FIG. 2. The helical flight assembly 180 extendscontinuously from the first end 168 of the housing 166 to the second end170 thereof. Uniformly positioned between the flight members 182 of theflight assembly 180 are a plurality of upwardly extending baffle members184 which are fixedly secured to the inner surface 176 of the side wall172 by welding or the like. The baffle members 184 preferably consist ofupwardly-extending portions of metal, the function of which will bedescribed below. The number of baffle members 184 to be used will vary,depending on site-specific considerations.

Positioned inwardly from the first end 168 of the housing 166 is a firstsection 190 shown in FIG. 2. The side wall 172 of the housing 166 at thefirst section 190 consists of an annular section of screening materialhereinafter designated as the primary screen unit 192. The primaryscreen unit 192 may be a continuous annular structure made of metal(e.g. stainless steel) having substantially the same diameter as theside wall 172 of the housing 166. Alternatively, the primary screen unit192 may actually consist of a plurality of individual arcuate screensections (not shown) secured together to form an integral structure. Themesh size of the primary screen unit 192 will preferably be not lessthan about 0.1 micron, although this size may vary depending on thecharacteristics of the materials being treated. It should also be notedthat the helical flight assembly 180 passes over the primary screen unit192 in order to ensure the efficient and continuous transport ofmaterials through the washing chamber 164.

The housing 166 further includes a second section 200 which ispositioned between the first section 190 and the second end 170 of thehousing 166. The side wall 172 of the housing 166 at the second section200 consists of an annular section of screening material hereinafterdesignated as the secondary screen unit 202. In a preferred embodiment,the secondary screen unit 202 will have the same basic structuralcharacteristics as the primary screen unit 192 described above.Specifically, the secondary screen unit 202 may consist of a continuousannular structure made of metal (e.g. stainless steel) havingsubstantially the same diameter as the side wall 172 of the housing 166.Alternatively, the secondary screen unit 202 may consist of a pluralityof individual arcuate screen sections (not shown) secured together toform an integral structure. The mesh size of the secondary screen unit202 will preferably be not less than about 0.1 micron, although thissize may vary depending on the characteristics of the materials beingtreated and other factors. It should also be noted that the helicalflight assembly 180 passes over the secondary screen unit 202 to againensure the efficient and continuous transport of materials through thewashing chamber 164. In a preferred embodiment as shown in FIG. 2, theprimary and secondary screen units 192, 202 are separated from eachother by an unperforated section 206 of the side wall 172.

With continued reference to FIG. 2, a tubular first conduit 208 isprovided, most of which is positioned within the interior region 174 ofthe housing 166. The first conduit 208 includes a first end 210 and asecond end 212. The first end 210 is connected to the supply ofsupplemental solvent 33 as described above. The second end 212terminates within the interior region 174 of the housing 166 near thefirst end 168 of the housing 166. Positioned on section 216 of the firstconduit 208 (e.g. between the first end 168 of the housing 166 and thefirst section 190 thereof) are multiple spray nozzles 220 which allowdelivery of the supplemental solvent 33 to materials within the housing166 before they enter the first section 190. In a preferred embodiment,about 15-30 spray nozzles 220 will be used, although this number mayvary, depending on a wide variety of site-specific considerations. Asnoted above, application of the supplemental solvent 33 using theforegoing components is optional, and will depend on a variety offactors including but not limited to the type of materials beingtreated, as well as the hydrocarbon contaminant composition to beremoved.

Also included as illustrated in FIG. 2 is a tubular second conduit 222,most of which is positioned within the interior region 174 of thehousing 166. The second conduit 222 includes a first end 224 and asecond end 226. The first end 224 is connected to the supply of washingwater 40 described above. The second end 226 terminates within the firstsection 190 of the housing 166. With continued reference to FIG. 2, thesecond conduit 222 includes a section 228 which is positioned directlyabove the primary screen unit 192. The section 228 includes a pluralityof spray nozzles 230 attached thereto which allow delivery of thewashing water 40 to materials within the housing 166 as they pass overthe primary screen unit 192. In a preferred embodiment, about 15-30spray nozzles 230 will be used, although this number may vary based on awide variety of site-specific considerations. In accordance with theoperational characteristics of the second conduit 222, it willeffectively function as first water delivery means in the housing 166.

Finally, as shown in FIG. 2, a tubular third conduit 236 is provided,most of which is positioned within the interior region 174 of thehousing 166. The third conduit 236 includes a first end 240 and a secondend 242. The first end 240 is connected to the supply of rinse water 72described above. The second end 242 terminates within the second section200 of the housing 166. The third conduit 236 shown in FIG. 2 alsoincludes a section 246 which is positioned directly above the secondaryscreen unit 202 as illustrated in FIG. 2. The section 246 furtherincludes a plurality of spray nozzles 248 attached thereto which allowdelivery of the rinse water 72 to materials within the housing 166 asthey pass over the secondary screen unit 202. In a preferred embodiment,about 15-30 spray nozzles 248 will be used, although this number mayagain vary, depending on a wide variety of factors. In accordance withthe operational characteristics of the third conduit 236, it willeffectively function as second water delivery means in the housing 166.

With continued reference to FIG. 2, a primary containment tank 250 isprovided which is positioned outside of the housing 166 of washingchamber 164. The tank 250 is of conventional design, and is preferablyconstructed of the same materials (e.g. stainless steel) used inconnection with the housing 166. While the size of the tank 250 may varydepending on the desired capacity of the washing chamber 164, the tank250 will preferably have a preferred capacity of about 250-500 gallons.In addition, the tank 250 is positioned directly beneath and spacedoutwardly from the first section 190 of the housing 166 (e.g. directlybeneath the primary screen unit 192). In this manner, the tank 250 maybe used to collect liquid and solid materials which pass through theprimary screen unit 192 from the interior region 174 of the housing 166.

A secondary containment tank 254 is also provided which is positionedoutside of the housing 166 of washing chamber 164. The tank 254 is ofconventional design, and is preferably of the same type and capacity asthe primary containment tank 250. In a preferred embodiment, the tank254 is positioned directly beneath and spaced outwardly from the secondsection 200 of the housing 166 (e.g. directly beneath the secondaryscreen unit 202). In this manner, the tank 254 may be used to collectmaterials which pass through the secondary screen unit 202 from theinterior region 174 of the housing 166.

Finally, the exterior surface 257 of the housing 166 is preferably infrictional engagement with a plurality of roller units 258 (only twobeing schematically shown in FIG. 2) which are operatively connected toa motor drive system (not shown). Each of the roller units 258 ispreferably made of rubber or resilient plastic, and is secured to asupport frame 260 using a metal U-shaped mounting bracket 262 which isconventional in structure and design.

In order to use the washing chamber 164, solid material 18 to beprocessed is first placed within the interior region 112 of thecontainment chamber 102. Solvent 22 is then combined with the solidmaterial 18 in the chamber 102 using the feed conduit 146 and associatedspray nozzles 152. The resulting mixture 26 is thereafter directedtoward the bottom wall 106 of the chamber 102 by the downwardly-angledwall 122. As the mixture 26 flows toward the bottom wall 106, it entersthe gap 120 illustrated in FIG. 2. The mixture 26 is then transportedupwardly by the feed auger 130 which is rotated using the motor 142(e.g. at an exemplary speed of about 5-20 rpm). The feed auger 130 notonly transports the mixture 26 in an efficient manner, but also agitatesand mixes the solid material 18 and solvent 22 to facilitate thedecontamination process.

The feed auger 130 ultimately delivers the mixture 26 to the chute 160in the rear wall 110 of the chamber 102. As shown in FIG. 2, the chute160 is positioned so that it extends into the open first end 168 of thehousing 166 associated with the washing chamber 164. As the mixture 26passes from the chute 160 into the washing chamber 164, the housing 166is rotated using the motor-driven roller units 258 (e.g. at an exemplaryspeed of about 5-20 rpm). Rotation of the housing 166 causescorresponding rotation of the helical flight assembly 180 therein whichmoves the mixture 26 through the housing 166. As the mixture 26 movestoward the first section 190 of the housing 166, it may be sprayed withthe supplemental solvent 33 using the first conduit 208 and associatedspray nozzles 220. The mixture 26 is thereafter moved by the helicalflight assembly 180 into the first section 190 where it comes in contactwith the primary screen unit 192. When the mixture 26 passes into thefirst section 190, washing water 40 is applied thereto from the secondconduit 222 and associated spray nozzles 230. The drainage product 54 asdescribed above moves through the primary screen unit 192 and iscollected within the primary containment tank 250 for subsequenttreatment as indicated below.

Continued rotation of the housing 166 causes the resulting purifiedsolid product (not shown) on the primary screen unit 192 to move towardand into the second section 200 of the housing 166. When the purifiedsolid product enters the second section 200, it comes in contact withthe secondary screen unit 202. Within the second section 200 of thehousing 166, the purified solid product is rinsed with rinse water 72supplied from the third conduit 236 and associated spray nozzles 248.The rinse water 72 which passes through the secondary screen unit 202contains a minimal amount of contaminants and solids, and is retainedwithin the secondary containment tank 254. As previously noted, therinse water 72 within the tank 254 may be used as the washing water 40which is directed back into the first section 190 of the washing chamber164.

Additional rotation of the housing 166 and helical flight assembly 180moves the resulting final solid product 86 toward and through the secondend 170 of the housing 166 where it may be collected and used asdesired. The treatment apparatus 100 of FIG. 2 operates in a highlyefficient manner to treat substantial amounts of contaminated solidmaterial. When properly configured in accordance with site-specificconsiderations, the treatment apparatus 100 is prospectively capable oftreating at least about 20 yd³ /hr. or more of solid material. In thisregard, the apparatus 100 is an effective system for implementing theprocesses described herein. However, as noted above, the presentinvention shall not be limited exclusively to the use of apparatus 100.Other systems with similar capabilities and different components mayalso be used.

Referring back to FIG. 1, the drainage product 54 from the containmenttank 52 beneath the washing chamber 30 is now treated to recover thesolvent 22 and water therefrom. Treatment of the drainage product 54 inaccordance with a preferred embodiment of the invention is illustratedin FIG. 1. In addition, the treatment process is schematicallyillustrated in the flow diagram of FIG. 3. As previously noted, thedrainage product 54 involves a combination of (1) the washing water 40;(2) the solvent 22 having the hydrocarbon contaminant compositiondissolved therein; and (3) finely-divided portions of the solid material18 small enough to pass through the primary screen member 38. Afterpassing through line 60, the drainage product 54 is pumped by pump 62into line 64. As the drainage product 54 passes through line 64, itenters into a first separating means 272 which is in fluid communicationwith the treatment unit 12. The first separating means 272 preferablyinvolves a primary cyclonic separator unit 276 of a type well known inthe art for separating mixtures of material. The cyclonic separator unit276 includes a chamber 278 having an upper end 280 and a lower end 282.As illustrated in FIG. 1, the lower end 282 tapers inwardly in order toform an inverted cone-like structure 284 having an apex 288. Thecyclonic separator unit 276 enables separation of the drainage product54 into various liquid and solid components. Specifically, the drainageproduct 54 enters the chamber 278 of the cyclonic separator unit 276 atthe upper end 280 thereof via line 64. The pump 62 introduces thedrainage product 54 into the cyclonic separator unit 276 at a fluidpressure sufficient to cause the drainage product 54 to begin rapidlyswirling therein. This pressure will normally be about 30-1500 psi. Itshould be noted that the selected fluid pressure within the foregoingrange will depend on the size and configuration of the cyclonicseparator unit 276. In a preferred embodiment, a fluid pressure shouldbe chosen in accordance with preliminary pilot tests so that internalforces within the cyclonic separator unit 276 will range from about600-1000 g. Swirling of the drainage product 54 in the foregoing mannercauses it to separate into a first fraction 290 and a second fraction292 (FIG. 3). Separation is accomplished in accordance with known andestablished physical principles associated with the operation ofcyclonic separation systems. In a preferred embodiment, the cyclonicseparator unit 276 uses a "closed apex design" in which materials areintermittently discharged. Specifically, fluid release from the cyclonicseparator unit 276 only occurs when the apex 288 of the unit 276 isopened. As a result, operation of the entire processing system 10 ismore precisely controlled. It should be noted that the first separatingmeans 272 shall not be exclusively limited to the use of cyclonicseparator unit 276. In contrast, other separation systems known in theart and suitable for the purposes set forth herein may also be usedincluding but not limited to conventional centrifuge systems (e.g.three-phase decanting centrifuge units), membrane filtration devices,and the like.

The first fraction 290 is predominantly organic in character, and willmostly consist of the solvent 22 having the hydrocarbon contaminantcomposition dissolved therein. The first fraction 290 may also includevery small amounts of residual water and residual solid materialstherein which will be removed as described below. The second fraction292 will be aqueous in character, and will primarily consist of thewashing water 40 in combination with finely-divided portions of solidmaterial 18 which passed through the primary screen member 38 into thecontainment tank 52. In accordance with fluid pressures generated withinthe processing system 10 by the pump 62, the first fraction 290 willleave the cyclonic separator unit 276 through a line 300 which isoperatively connected to the upper end 280 of the unit 276. In contrast,the second fraction 292 will leave the cyclonic separator unit 276through the lower end 282 (e.g. the apex 288) where it will flow througha line 302 into a sludge tank 304 (FIG. 1) of conventional design havinga mixing blade 306 therein which is operatively connected to a standardelectric motor 308.

The first fraction 290 passes from line 300 at a pressure of about30-1500 psi (generated by the pump 62) into a second separating means312 which is in fluid communication with the first separating means 272.The second separating means 312 preferably involves a secondary cyclonicseparator unit 314 of a type well known in the art for the purposesdescribed herein. The secondary cyclonic separator unit 314 is in fluidcommunication with and downstream from the primary cyclonic separatorunit 276 as shown in FIG. 1. In a preferred embodiment, the secondarycyclonic separator unit 314 is of substantially the same design as theprimary cyclonic separator unit 276, and includes a chamber 316 havingan upper end 318 and a lower end 320. As schematically illustrated inFIG. 1, the lower end 320 tapers inwardly to form an inverted cone-likestructure 330 having an apex 332. In accordance with the presentinvention, the first fraction 290 enters the chamber 316 of the cyclonicseparator unit 314 at the upper end 318 thereof via line 300. The firstfraction 290 enters the cyclonic separator unit 314 at a fluid pressuresufficient to cause the first fraction 290 to rapidly swirl therein.This pressure will normally be about 30-1500 psi as stated above. Itshould be noted that the selected fluid pressure within the foregoingrange will depend on the size and configuration of the cyclonicseparator unit 314. In a preferred embodiment, a fluid pressure shouldbe chosen in accordance with preliminary pilot tests so that internalforces within the cyclonic separator unit 314 will range from about600-1000 g. Swirling of the first fraction 290 causes it to separateinto a third fraction 334 and a fourth fraction 336 (FIG. 3). Separationis again accomplished in accordance with known and established physicalprinciples involving cyclonic separation systems. In a preferredembodiment, the secondary cyclonic separator unit 314 uses a "closedapex design" in which materials are intermittently discharged asdescribed above regarding the primary cyclonic separator unit 276. Itshould again be noted that the second separating means 312 shall not beexclusively limited to cyclonic separator unit 314. Instead, otherseparation systems known in the art and suitable for the purposes setforth herein may also be used including but not limited to conventionalcentrifuge systems (e.g. three-phase decanting centrifuge units),membrane filtration devices, and the like.

The third fraction 334 will be organic in character, and will consist ofthe solvent 22 having the hydrocarbon contaminant composition dissolvedtherein. The fourth fraction 336 will be aqueous in character, and willprimarily consist of very small amounts of residual water and residualsolid materials which remained in the first fraction 290 afterseparation of the drainage product 54 into the first and secondfractions 290, 292. The third fraction 334 will thereafter leave thesecondary cyclonic separator unit 314 through line 340 which isoperatively connected to the upper end 318 of the unit 314. The fourthfraction 336 will leave the cyclonic separator unit 314 through thelower end 320 thereof (e.g. the apex 332). The fourth fraction 336 willthereafter flow through line 342 into the sludge tank 304 (FIG. 1).Within the sludge tank 304, the fourth fraction 336 is combined with thesecond fraction 292 using the mixing blade 306 driven by the motor 308.As shown in FIG. 3, the second fraction 292 combines with the fourthfraction 336 to form a sludge product 344 which is routed through line346 into a pump 348 (e.g. of the same general design as pump 48). Thesludge product 344 is thereafter directed by the pump 348 into anin-line mixing compartment 350 via line 352.

With continued reference to FIG. 1, the processing system 10 preferablyincludes a tank 354 of conventional design having a mixing blade 356therein which is driven by a standard electric motor 360. The tank 354includes a supply of a chemical flocculent 362 therein. Exemplaryflocculent materials suitable for this purpose include but are notlimited to anionic, cationic, and/or zwitterionic colloid compositionswhich are well known in the art. A specific composition that willfunction effectively for the foregoing purposes is a product sold underthe name PERCOL™ 722 by Allied Colloids of Suffolk, Va. (U.S.A.). Otherknown colloid compositions are commercially available from the CalgonCorp. of Pittsburgh, Pa. (U.S.A.). The flocculent 362 is added to thesludge product 344 in order to cause fine solid materials therein toflocculate into larger units which are more readily removed insubsequent parts of the system 10. The flocculent 362 is fed from thetank 354 into a line 364 which leads into a pump 366 (e.g. of the sametype as pump 48). The pump 366 thereafter directs the flocculent 362into the in-1 line mixing compartment 350 via line 368. Within themixing compartment 350, the flocculent 362 combines with the sludgeproduct 344 to flocculate fine solid materials as described above. Theflocculated sludge product 370 (FIG. 3) is then directed through line372 into a third separating means 376 which is in fluid communicationwith the first separating means 272 and the second separating means 312.In a preferred embodiment, the third separating means 376 consists of acentrifuge unit 378 (e.g. of standard flow-through two-phase design).However, other conventional separation systems may be used instead ofthe centrifuge unit 378, with the present invention not being limited toany particular separation system. For example, cyclonic separationsystems, membrane filtration systems, and the like may also be used.

Within the centrifuge unit 378, the flocculated sludge product 370 iscentrifugally separated into a fifth fraction 380 and sixth fraction 382(FIG. 3). Exemplary rotational speeds within the centrifuge unit 378will be about 1000-6000 rpm. The specific speed to be used within thisrange will depend on the size and configuration of the centrifuge unit378 being used. In a preferred embodiment, a rotational speed should bechosen in accordance with preliminary pilot tests so that internalforces within the selected centrifuge unit 378 will range from about3000-10,000 g. The fifth fraction 380 consists of water from the secondfraction 292 and residual water from the fourth fraction 336 whichcombine to produce a supply of recycled water 384 as illustrated in FIG.3. The sixth fraction 382 consists of finely-divided portions of solidmaterial from the second fraction 292 and residual solid materials fromthe fourth fraction 336. The sixth fraction 382 is routed out of thecentrifuge unit 378 via line 386, and is thereafter retained or disposedof as desired. Because the sixth fraction 382 is substantially free fromthe initial hydrocarbon contaminant composition, it may be returned tothe environment in combination with the final solid product 86 describedabove (especially if soil compositions are involved.)

The fifth fraction 380 (which consists of the supply of recycled water384) is thereafter routed through line 390 and into pump 392 (e.g. ofthe same type as pump 48). The pump 392 directs the supply of recycledwater 384 through line 394 which terminates at the second section 69within the washing chamber 30. In a preferred embodiment, the line 394terminates directly above the secondary screen member 70. The supply ofrecycled water 384 may thereafter be used as rinse water 72 in thesecond section 69 of the washing chamber 30 in order to rinse additionalamounts of solid material which enter the processing system 10. In thismanner, conservation of water is achieved, thereby minimizing theenvironmental impact caused by processing system 10 and greatlyimproving its operational efficiency. It should be noted that therecycled water 384 may be collected in a separate tank (not shown) priorto use as the rinse water 72, or may be used immediately in the secondsection 69 as described above. Likewise, lines 390 and 394 shallcollectively be designated as first conduit means for transferring therecycled water 384 (e.g. the fifth fraction 380) from the thirdseparating means 376 to the washing chamber 30.

The third fraction 334 (which includes the solvent 22 combined with thehydrocarbon contaminant composition) is passed through line 340 (FIG. 1)into a solvent collecting tank 400 having a first compartment 402 and asecond compartment 404. The line 340 is in fluid communication with thefirst compartment 402 as illustrated. After passing through line 340,the third fraction 334 enters the first compartment 402 of tank 400 andis temporarily collected therein.

As described below, the hydrocarbon materials combined with the solvent22 will be ultimately be separated from the solvent 22. The hydrocarbonmaterials may then be combusted as fuel, depending on the chemicalnature of the materials. If the hydrocarbon materials are usable asfuel, they may be combusted within a conventional generator system 410schematically illustrated in FIG. 1. An exemplary generator system 410will include an internal combustion engine 412 of standard design whichis operatively connected to a standard electrical generator unit 414. Ina preferred embodiment, the engine 412 will include a fluid coolingsystem known in the art comprising a radiator 418 preferably havingglycol-type coolant therein. To improve the efficiency of system 10regarding subsequent purification (e.g. distillation) of the thirdfraction 334, the third fraction 334 may be pre-heated (e.g. to apreferred temperature of about 100°-150° C.). Pre-heating reduces theamount of energy consumption in subsequent stages of the system 10. In apreferred embodiment wherein the generator system 410 is used, heatingmeans 420 may be provided in the form of a conventional heat exchanger424 which is operatively connected to the radiator 418. As schematicallyshown in FIG. 1, the heat exchanger 424 includes a first conduit 426 influid communication with the radiator 418. The first conduit 426 is alsoconnected to a second conduit 428 within a housing 430 which forms partof the heat exchanger 424. The second conduit 428 is thereafterconnected to a third conduit 432 which leads out of the housing 430 andback to the radiator 418. Using these components, heated coolant fluidfrom the radiator 418 is passed through the housing 430 via the first,second, and third conduits 426, 428, 432. To pre-heat the third fraction334, it is fed from the tank 400 through line 434 which is connected toa pump 438 (e.g. of the same type as pump 48). The pump 438 thereafterdirects the third fraction 334 through a line 440 which leads into thehousing 430 of the heat exchanger 424. Within the housing 430, a fourthconduit 442 is provided which is connected to the line 440. Asschematically illustrated in FIG. 1, the fourth conduit 442 and secondconduit 428 (both of which are preferably manufactured of copper orother heat conductive metal) are positioned directly adjacent to andagainst each other within the housing 430. In this manner, heat from thehot coolant fluid passing through the second conduit 428 is conductivelytransferred to the fourth conduit 442. As a result, the third fraction334 is heated as it passes through the fourth conduit 442. The heatedthird fraction 334 leaves the fourth conduit 442 (and heat exchanger424) via line 448 as illustrated. It should be noted that use of thegenerator system 410 (and heat exchanger 424) is optional and not arequired part of the processing system 10. If an electrical generatorsystem is desired, a number of different generator units may be used,and the present invention shall not be limited to any particular system.Also, the present invention shall not be limited to the heat exchanger424 and components described above. Alternative pre-heating means may beused including but not limited to conventional jacket-type electricalheating systems and other comparable units.

The third fraction 334 passing through line 448 is thereafter routedinto a fourth separating means 450 which is in fluid communication withthe second separating means 312. The fourth separating means 450preferably involves a fractional distillation unit 454 of conventionaldesign. In particular, an exemplary fractional distillation unit 454will consist of a reboiler to vaporize liquids, a condenser to condensevapors to a liquid state, and trays or packing material to provideliquid/vapor contact (not shown), all of which are standard components.Within the fractional distillation unit 454, the third fraction 334 isheated to a temperature sufficient to vaporize and separate the solvent22 from the hydrocarbon contaminant composition. The temperaturenecessary to accomplish this goal will vary, depending on the chemicalnature of the solvent 22 being used. With respect to the terpenecompositions described above, the distillation temperature of interestwill broadly range from about 150°-200° C. Table 1 provides temperatureranges at which about 95% of the solvent of interest will be vaporizedand removed from the third fraction 334:

                  TABLE 1                                                         ______________________________________                                        Solvent      Distillation Temp. Range (°C.)                            ______________________________________                                        alpha-pinene 155-157                                                          beta-pinene  166-168                                                          limonene     175-177                                                          terpinolene  189-191                                                          alpha-terpinene                                                                            178-180                                                          gamma-terpinene                                                                            180-182                                                          beta-phellandrene                                                                          168-170                                                          para-cymene  176-178                                                          1,4-cineole  172-174                                                          1,8-cineole  175-177                                                          ______________________________________                                    

Use of the fractional distillation unit 454 will generate a seventhfraction 456 and an eighth fraction 458 (FIG. 3). The seventh fraction456 will consist of solvent 22, while the eighth fraction 458 willconsist of the hydrocarbon contaminant composition. The seventh fraction456 (which specifically consists of a supply of recovered solvent 22) isthereafter routed via line 460 into the second compartment 404 of thetank 400 where it is collected for subsequent use as described below.Within the tank 400, it is preferred that the seventh fraction 456 beaugmented with a supply of make-up solvent 464 (preferably of the sametype as solvent 22). This is due to evaporative losses of the solvent 22during the foregoing procedures, as well as losses encountered duringdistillation. The make-up solvent 464 is supplied to the secondcompartment 404 of the tank 400 via line 466. A determination as to howmuch make-up solvent 464 will be needed (if any) can be undertaken inaccordance with site-specific preliminary pilot studies. However, it isreasonable to assume that at least about a 10% solvent loss will occuras a result of distillation and processing in system 10.

The seventh fraction 456 (and any added make-up solvent 464) isthereafter routed via line 468, pump 470 (e.g. of the same type as pump48), and line 472 back into the containment vessel 14 for use as solvent22 in the treatment any additional amounts of solid material which enterthe processing system 10. In this manner, the system 10 enables theefficient and economical use of solvent materials with a minimal degreeof environmental impact. It should also be noted that all or part of theseventh fraction 456 (and any make-up solvent 464 associated therewith)may be routed via line 474 into the washing chamber 30 for use as thesupply of supplemental solvent 33 if needed. Likewise, lines 460, 468,and 472 shall collectively be designated as second conduit means fortransferring the seventh fraction 456 from the fourth separating means450 to the containment vessel 14.

Finally, the eighth fraction 458 (consisting of the isolated hydrocarboncontaminant composition) is routed via line 476 from the fractionaldistillation unit 454 into an optional filter 478 of conventionaldesign. An exemplary filter 478 will consist of a standard 100 micronpaper filter unit with a supporting screen structure (not shown).However, other conventional filter materials may be used (includingmembrane systems known in the art), and the present invention shall notbe limited to any particular filter media. The filter 478 is designed toremove any residual fines and other extraneous solid matter from thehydrocarbon contaminant composition. Filtration in this manner is ofparticular importance if the hydrocarbon contaminant composition is tobe combusted as fuel. The collected solids 479 (if any) may be then bedisposed of or placed back into the containment vessel 14 via line 480for treatment (since they will have at least some of the hydrocarboncontaminant composition associated therewith). The filtered eighthfraction 481 may thereafter be stored, used as fuel, or disposed of asdesired. If the filtered eighth fraction 481 is suitable for use as afuel product (e.g. if it consists of petroleum products such as dieselfuel or fuel oil), it may be routed through line 482 into a fuel storagetank 484. From the fuel storage tank 484, the filtered eighth fraction481 may be used (e.g. burned or combusted) as fuel in a number of ways.For example, as illustrated in FIG. 1, the filtered eighth fraction 481may be sent through line 486 to the internal combustion engine 412 ofthe generator system 410 for use as fuel. Likewise, all or part of thefiltered eighth fraction 481 may be routed by line 488 to a burner-typeheating apparatus 490 used in the fractional distillation unit 454.

As described herein, the processing system 10 enables the rapid andefficient treatment of soil and other solid materials contaminated withhydrocarbon compositions. The closed-loop nature of the system 10enables conservation of water and solvent materials, thereby reducingenvironmental impact and operating costs. Various modifications to thesystem 10 may be made, depending on a wide variety of external factorsincluding but not limited to (1) the type of solid material beingdecontaminated; (2) the amount of solid material to be treated; and (3)the chemical nature of the hydrocarbon contaminant composition involved.For example, an alternative system 500 is illustrated in FIG. 4. All ofthe components and operating characteristics of system 500 aresubstantially identical to those of system 10 unless otherwise indicatedbelow. With reference to FIG. 4, the system 500 is simplified to treatsolid materials with a reduced degree of contamination. For example, insystem 500, the second section 69 of the washing chamber 30 has beeneliminated, along with the secondary screen member 70 and theapplication of rinse water 72. Instead, the purified solid product 68 isremoved from the washing chamber 30 directly after the application ofwashing water 40 in the first section 36 of the chamber 30. In thesystem 500, the supply of recycled water 384 generated from thecentrifuge unit 378 is routed via line 390, pump 392, and line 394directly to the containment tank 42 as illustrated. The recycled water384 is then used as the washing water 40 in the first section 36 of thechamber 30 as described above. The rinsing step associated with thesecondary screen member 70 in the embodiment of FIG. 1 is primarilydesigned as a "polishing" step, and may not be absolutely necessary incertain cases involving minimally-contaminated solid materials.

The system 500 has also been simplified to omit the second separatingmeans 312 (e.g. the secondary cyclonic separator unit 314) along withline 342. Instead, the first fraction 290 from the first separatingmeans 272 (e.g. the primary cyclonic separator unit 276) is routedthrough lines 300, 340 into subsequent parts of the system 500 fortreatment as described above with respect to system 10. As previouslyindicated, the first fraction 290 is organic in character and primarilyincludes the solvent 22 in combination with the hydrocarbon contaminantcomposition. With continued reference to FIG. 4, the first fraction 290is ultimately introduced into the fractional distillation unit 454, withsolvent 22 being separated from the hydrocarbon contaminant compositionin order to generate a supply of recovered solvent 22.

In the embodiment of FIG. 4, the second fraction 292 (which is aqueousin character) is routed from the cyclonic separator unit 276 throughline 302 into the sludge tank 304. The second fraction 292 issubsequently treated in the centrifuge unit 378 to separate water andsolid materials as described above relative to system 10. It should benoted that, in the alternative system 500, the centrifuge unit 378 shallbe considered as the second separating means, and the fractionaldistillation unit 454 shall be considered as the third separating meanssince the secondary cyclonic separator unit 314 has been omitted.Accordingly, in the system 500, the first separating means (the cyclonicseparator unit 276) is in fluid communication with both the secondseparating means (the centrifuge unit 378) and the third separatingmeans (the fractional distillation unit 454).

In addition, it is important to emphasize that the basic processingtechniques and components described above may be further varied in viewof numerous site-specific considerations. The alternative embodiment ofFIG. 4 represents only one example wherein modifications have been madeto the preferred system of FIG. 1. Regarding alternative embodiments,the present invention shall not be exclusively limited to the system 500of FIG. 4. For example, the system 500 may be further modified toinclude a washing chamber 30 having the second section 69 and secondaryscreen member 70 therein. The functional capabilities of thesecomponents are described above. If such a further alternative systemwere used (which omitted the second separating means 312 but includedthe second section 69 with the secondary screen member 70 therein), thesupply of recycled water 384 generated from the centrifuge unit 378would be routed via line 390, pump 392, and line 394 to the secondsection 69 and used as rinse water therein. Likewise, the use of screenmembers in the washing chambers of systems 10, 500 may be eliminated andsubstituted with other conventional and equivalent support structures.

To demonstrate the effectiveness of the present invention in treatingsolid materials contaminated with hydrocarbon compositions, thefollowing Examples are provided:

EXAMPLE 1

In this Example, a mixture of soil, clay, sand and gravel containingabout 0.6-1.5% by weight waste crude oil was treated with a selectedterpene solvent in accordance with the present invention. Specifically,limonene was used as the terpene solvent in a pilot-scale systemcomparable to the treatment apparatus 100 illustrated in FIG. 2. Thecontaminated mixture was combined with solvent and washed in a singlestep. The following parameters were used as listed in Table 2:

                  TABLE 2                                                         ______________________________________                                        Parameter         Specification                                               ______________________________________                                        High Pressure Water Wash                                                                        12.58 ± 0.102 l/min.                                     Solvent Flow Rate 80.0 ml/min.                                                System Volume (total)                                                                           78.9 l                                                      Solids Feed       1.0 kg/min.                                                 Aqueous Fluid Turnover                                                                          6.3 min.                                                    Rotational Speed of                                                                             8.03 ± 1.52 rpm                                          Washing Chamber                                                               Retention Time (total)                                                                          97.30 ± 4.50 sec.                                        Contact Time between                                                                            64.8 sec.                                                   Mixture and Solvent                                                           ______________________________________                                    

Approximately 95% of the treated mixture was recovered for analysis.Analysis was conducted using conventional supercritical fluid extractionprocedures followed by gas chromatograph analysis with a flameionization detector. Analytical results indicated that about 98.44%(±1.45%) of the hydrocarbon contaminants were removed from the solidmaterials. Washing water quality was monitored on-line for pH,turbidity, temperature, conductivity, salinity, oxidative reductivepotential, and dissolved oxygen. The water was determined to have notoxicity when evaluated using an assay system recommended by the U.S.Environmental Protection Agency sold under the trademark POLYTOX byPolybac, Inc. of Bethlehem, Pa. (U.S.A.). During the decontaminationprocedure, the water had a pH of 8.45-8.48, a temperature of 21.9°-23.5°C., a conductivity of 0.476-0.492 mS/cm, a salinity of 0.2%, anoxidative reductive potential of 207-210 mV, and a dissolved oxygencontent of 6.83-9.27 mg/l. Turbidity increased from an initial level of4 to >800 NTU as the capacity of the pilot system was reached. As aresult, the water became milky from the presence of non-coalescedterpenes. However, the water cleared in about 36 hours. With theaddition of a moderately cationic flocculent (e.g. a composition soldunder the name PERCOL™ 722 by Allied Colloids of Suffolk, Va. (U.S.A.)),samples of the water cleared in less than about 24 hours.

EXAMPLE 2

In the pilot-scale system described above in Example 1, gravel materialscontaining about 1.33% by weight (±0.2%) crude oil were processed. Thegravel materials (individually sized between about 2-20 mm in diameter)were specifically contaminated with 25.4° API crude oil containing62.68% by weight aliphatic hydrocarbons, 22.53% by weight aromatichydrocarbons, 6.38% by weight pentane soluble resins, and 6.40% byweight nonpentane soluble resins (asphaltenes). Elemental analysisindicated that the crude oil also contained 0.35% by weight nitrogen and3.24% by weight sulfur. Using the process of the present invention asdescribed above in Example 1, contamination of the gravel materials wasreduced to 0.018% using a gravel feed rate of 200 g/min., a washingchamber rotational speed of 8.0 rpm, and a terpene (limonene) feed rateof 80 ml/min. Treated samples were evaluated for moisture retention byevaporation at 180° C. and residual hydrocarbon content by U.S.Environmental Protection Agency method number 3540. Residual moisturewas indicated to be 1.6% (±0.2%).

As indicated in the foregoing Examples and described above, the presentinvention represents an advance in the art of decontaminationtechnology. It enables the efficient removal of hydrocarbon contaminantsfrom solid materials in a closed-loop system which reduces the amount ofwater and solvents needed for processing. Having herein describedpreferred embodiments of the invention, it is anticipated that suitablemodifications may be made thereto by individuals skilled in the artwhich nonetheless remain within the scope of the invention. Accordingly,the present invention shall only be construed in connection with thefollowing claims:

The invention that is claimed is:
 1. A method for removing hydrocarboncontaminants from solid materials comprising the steps of:providing atreatment system comprising a containment vessel and a washing chamber,said washing chamber comprising at least one screen member therein andsaid containment vessel comprising a supply of solid material therein,said solid material being combined with at least one hydrocarboncontaminant composition; providing a supply of a solvent designed toremove said hydrocarbon contaminant composition from said solidmaterial, said solvent comprising at least one terpene composition;combining said solid material in said containment vessel with saidsolvent in order to form a mixture; placing said mixture on said screenmember in said washing chamber; applying a supply of water to saidmixture on said screen member, said applying of said water to saidmixture producing a drainage product which passes through said screenmember and a purified solid product which remains on said screen memberand does not pass therethrough, said drainage product comprising saidwater, said solvent with said hydrocarbon contaminant compositiondissolved therein, and finely-divided portions of said solid materialsmall enough to pass through said screen member, with said purifiedsolid product comprising remaining portions of said solid material largeenough to prevent passage thereof through said screen member; removingsaid purified solid product from said treatment system, said purifiedsolid product having said hydrocarbon contaminant composition removedtherefrom; separating said drainage product into a first fraction and asecond fraction, said first fraction comprising said solvent with saidhydrocarbon contaminant composition dissolved therein, and said secondfraction comprising said water and said finely-divided portions of saidsolid material which passed through said screen member; separating saidfirst fraction into a third fraction and a fourth faction, said thirdfraction comprising said solvent with said hydrocarbon contaminantcomposition dissolved therein, and said fourth fraction comprising anyresidual water and residual solid material which remained in said firstfraction after said separating of said drainage product into said firstfraction and said second fraction; combining said second fraction andsaid fourth fraction to form a sludge product; separating said sludgeproduct into a fifth fraction and a sixth fraction, said fifth fractioncomprising said water from said second fraction and said residual waterfrom said fourth fraction which combine to produce a supply of recycledwater, with said sixth fraction comprising said finely-divided portionsof said solid material from said second fraction and said residual solidmaterial from said fourth fraction; separating said third fraction intoa seventh fraction and an eighth fraction, said seventh fractioncomprising a supply of recovered solvent, and said eighth fractioncomprising said hydrocarbon contaminant composition; supplying saidcontainment vessel with said supply of recovered solvent in order totreat any additional amounts of solid material which enter saidtreatment system; and supplying said washing chamber with said supply ofrecycled water so that said recycled water may be applied to saidadditional amounts of solid material which enter said treatment system.2. The method of claim 1 further comprising the step of combining saidsludge product with at least one chemical flocculent prior to saidseparating of said sludge product into said fifth fraction and saidsixth fraction.
 3. The method of claim 1 wherein said separating of saidsludge product into said fifth fraction and said sixth fractioncomprises the steps of:providing a centrifuge unit; introducing saidsludge product into said centrifuge unit; rotating said sludge productwithin said centrifuge unit at a rotational speed sufficient to separatesaid sludge product into said fifth fraction and said sixth fraction;and removing said fifth fraction and said sixth fraction from saidcentrifuge unit.
 4. The method of claim 1 further comprising the step ofheating said third fraction prior to said separating of said thirdfraction into said seventh fraction and said eighth fraction.
 5. Themethod of claim 1 further comprising the steps of filtering said eighthfraction in order to remove any extraneous solid matter therefrom, andtransferring said extraneous solid matter into said containment vesselof said treatment system for subsequent treatment thereof.
 6. The methodof claim 5 further comprising the step of combusting said hydrocarboncontaminant composition from said eighth fraction after said filteringof said eighth fraction.
 7. The method of claim 1 wherein saidseparating of said drainage product into said first fraction and saidsecond fraction comprises the steps of:providing a primary cyclonicseparator unit; introducing said drainage product into said primarycyclonic separator unit at a fluid pressure sufficient to cause saiddrainage product to begin rapidly swirling therein, said swirling ofsaid drainage product causing said drainage product to separate intosaid first fraction and said second fraction; and removing said firstfraction and said second fraction from said primary cyclonic separatorunit.
 8. The method of claim 7 wherein said separating of said firstfraction into said third fraction and said fourth fraction comprises thesteps of:providing a secondary cyclonic separator unit in fluidcommunication with and downstream from said primary cyclonic separatorunit; introducing said first fraction into said secondary cyclonicseparator unit at a fluid pressure sufficient to cause said firstfraction to begin rapidly swirling therein, said swirling of said firstfraction causing said first fraction to separate into said thirdfraction and said fourth fraction; and removing said third fraction andsaid fourth fraction from said secondary cyclonic separator unit.
 9. Themethod of claim 1 wherein said terpene composition is selected from thegroup consisting of alpha-pinene, beta-pinene, limonene, terpinolene,alpha-terpinene, gamma-terpinene, beta-phellandrene, para-cymene,1,4-cineole, and 1,8-cineole.
 10. The method of claim 1 wherein saidseparating of said third fraction into said seventh fraction and saideighth fraction comprises the steps of:providing a fractionaldistillation unit; introducing said third fraction into said fractionaldistillation unit; heating said third fraction in said fractionaldistillation unit in an amount sufficient to fractionally distill saidthird fraction and generate said seventh fraction and said eighthfraction from said third fraction; and removing said seventh fractionand said eighth fraction from said fractional distillation unit.
 11. Amethod for removing hydrocarbon contaminants from solid materialscomprising the steps of:providing a treatment system comprising acontainment vessel and a washing chamber, said washing chambercomprising a first section comprising at least one primary screen membertherein and a second section comprising at least one secondary screenmember therein, said second section of said washing chamber beingpositioned downstream from said first section, said containment vesselfurther comprising a supply of solid material therein, said solidmaterial being combined with at least one hydrocarbon contaminantcomposition; providing a supply of a solvent designed to remove saidhydrocarbon contaminant composition from said solid material, saidsolvent comprising at least one terpene composition; combining saidsolid material in said containment vessel with said solvent in order toform a mixture; placing said mixture on said primary screen member insaid first section of said washing chamber; applying a supply of washingwater to said mixture on said primary screen member, said applying ofsaid washing water to said mixture producing a drainage product whichpasses through said primary screen member and a purified solid productwhich remains on said primary screen member and does not passtherethrough, said drainage product comprising said washing water, saidsolvent with said hydrocarbon contaminant composition dissolved therein,and finely-divided portions of said solid material small enough to passthrough said primary screen member, with said purified solid productcomprising remaining portions of said solid material large enough toprevent passage thereof through said primary screen member; transferringsaid purified solid product to said secondary screen member in saidsecond section of said washing chamber; applying a supply of rinse waterto said purified solid product on said secondary screen member, saidrinse water passing through said secondary screen member; transferringsaid rinse water to said first section of said washing chamber afterpassage of said rinse water through said secondary screen member, saidrinse water thereafter being used in said first section of said washingchamber to wash any additional amounts of solid material which entersaid treatment system; removing said purified solid product from saidtreatment system after said applying of said rinse water thereto, saidpurified solid product having said hydrocarbon contaminant compositionremoved therefrom; separating said drainage product into a firstfraction and a second fraction, said first fraction comprising saidsolvent with said hydrocarbon contaminant composition dissolved therein,and said second fraction comprising said washing water from said firstsection of said washing chamber and said finely-divided portions of saidsolid material which passed through said primary screen member;separating said first fraction into a third fraction and a fourthfaction, said third fraction comprising said solvent with saidhydrocarbon contaminant composition dissolved therein, and said fourthfraction comprising any residual washing water and residual solidmaterial which remained in said first fraction after said separating ofsaid drainage product into said first fraction and said second fraction;combining said second fraction and said fourth fraction to form a sludgeproduct; separating said sludge product into a fifth fraction and asixth fraction, said fifth fraction comprising said washing water fromsaid second fraction and said residual washing water from said fourthfraction which combine to produce a supply of recycled water, with saidsixth fraction comprising said finely-divided portions of said solidmaterial from said second fraction and said residual solid material fromsaid fourth fraction; separating said third fraction into a seventhfraction and an eighth fraction, said seventh fraction comprising asupply of recovered solvent, and said eighth fraction comprising saidhydrocarbon contaminant composition; supplying said containment vesselwith said supply of recovered solvent in order to treat said additionalamounts of solid material which enter said treatment system; andtransferring said supply of recycled water to said second section ofsaid washing chamber, said recycled water thereafter being used in saidsecond section of said washing chamber as said rinse water in order torinse said additional amounts of solid material which enter saidtreatment system.
 12. The method of claim 11 further comprising the stepof combining said sludge product with at least one chemical flocculentprior to said separating of said sludge product into said fifth fractionand said sixth fraction.
 13. The method of claim 11 wherein saidseparating of said sludge product into said fifth fraction and saidsixth fraction comprises the steps of:providing a centrifuge unit;introducing said sludge product into said centrifuge unit; rotating saidsludge product within said centrifuge unit at a rotational speedsufficient to separate said sludge product into said fifth fraction andsaid sixth fraction; and removing said fifth fraction and said sixthfraction from said centrifuge unit.
 14. The method of claim 11 furthercomprising the step of heating said third fraction prior to saidseparating of said third fraction into said seventh fraction and saideighth fraction.
 15. The method of claim 11 further comprising the stepsof filtering said eighth fraction in order to remove any extraneoussolid matter therefrom, and transferring said extraneous solid matterinto said containment vessel of said treatment system for subsequenttreatment thereof.
 16. The method of claim 15 further comprising thestep of combusting said hydrocarbon contaminant composition from saideighth fraction after said filtering of said eighth fraction.
 17. Themethod of claim 11 wherein said separating of said drainage product intosaid first fraction and said second fraction comprises the stepsof:providing a primary cyclonic separator unit; introducing saiddrainage product into said primary cyclonic separator unit at a fluidpressure sufficient to cause said drainage product to begin rapidlyswirling therein, said swirling of said drainage product causing saiddrainage product to separate into said first fraction and said secondfraction; and removing said first fraction and said second fraction fromsaid primary cyclonic separator unit.
 18. The method of claim 17 whereinsaid separating of said first fraction into said third fraction and saidfourth fraction comprises the steps of:providing a secondary cyclonicseparator unit in fluid communication with and downstream from saidprimary cyclonic separator unit; introducing said first fraction intosaid secondary cyclonic separator unit at a fluid pressure sufficient tocause said first fraction to begin rapidly swirling therein, saidswirling of said first fraction causing said first fraction to separateinto said third fraction and said fourth fraction; and removing saidthird fraction and said fourth fraction from said secondary cyclonicseparator unit.
 19. The method of claim 11 wherein said terpenecomposition is selected from the group consisting of alpha-pinene,beta-pinene, limonene, terpinolene, alpha-terpinene, gamma-terpinene,beta-phellandrene, para-cymene, 1,4-cineole, and 1,8-cineole.
 20. Themethod of claim 11 wherein said separating of said third fraction intosaid seventh fraction and said eighth fraction comprises the stepsof:providing a fractional distillation unit; introducing said thirdfraction into said fractional distillation unit; heating said thirdfraction in said fractional distillation unit in an amount sufficient tofractionally distill said third fraction and generate said seventhfraction and said eighth fraction from said third fraction; and removingsaid seventh fraction and said eighth fraction from said fractionaldistillation unit.
 21. A method for removing hydrocarbon contaminantsfrom solid materials comprising the steps of:providing a treatmentsystem comprising a containment vessel and a washing chamber, saidwashing chamber comprising at least one screen member therein and saidcontainment vessel comprising a supply of solid material therein, saidsolid material being combined with at least one hydrocarbon contaminantcomposition; providing a supply of a solvent designed to remove saidhydrocarbon contaminant composition from said solid material, saidsolvent comprising at least one terpene composition; combining saidsolid material in said containment vessel with said solvent in order toform a mixture; placing said mixture on said screen member in saidwashing chamber; applying a supply of water to said mixture on saidscreen member, said applying of said water to said mixture producing adrainage product which passes through said screen member and a purifiedsolid product which remains on said screen member and does not passtherethrough, said drainage product comprising said water, said solventwith said hydrocarbon contaminant composition dissolved therein, andfinely-divided portions of said solid material small enough to passthrough said screen member, with said purified solid product comprisingremaining portions of said solid material large enough to preventpassage thereof through said screen member; removing said purified solidproduct from said treatment system, said purified solid product havingsaid hydrocarbon contaminant composition removed therefrom; separatingsaid drainage product into a first fraction and a second fraction, saidfirst fraction comprising said solvent with said hydrocarbon contaminantcomposition dissolved therein, and said second fraction comprising saidwater and said finely-divided portions of said solid material whichpassed through said screen member; separating said water from saidfinely-divided portions of said solid material in said second fractionso that said water is recovered from said second fraction in order togenerate a supply of recycled water; separating said solvent from saidhydrocarbon contaminant composition in said first fraction so that saidsolvent is recovered from said first fraction in order to generate asupply of recovered solvent; supplying said containment vessel with saidsupply of recovered solvent in order to treat any additional amounts ofsolid material which enter said treatment system; and supplying saidwashing chamber with said supply of recycled water so that said recycledwater may be applied to said additional amounts of solid material whichenter said treatment system.
 22. The method of claim 21 wherein saidseparating of said drainage product into said first fraction and saidsecond fraction comprises the steps of:providing a cyclonic separatorunit; introducing said drainage product into said cyclonic separatorunit at a fluid pressure sufficient to cause said drainage product tobegin rapidly swirling therein, said swirling of said drainage productcausing said drainage product to separate into said first fraction andsaid second fraction; and removing said first fraction and said secondfraction from said cyclonic separator unit.
 23. The method of claim 21wherein said separating of said water from said finely-divided portionsof said solid material in said second fraction comprises the stepsof:providing a centrifuge unit; introducing said second fraction intosaid centrifuge unit; rotating said second fraction within saidcentrifuge unit at a rotational speed sufficient to separate said secondfraction into said water and said finely-divided portions of said solidmaterial; and removing said water and said finely-divided portions ofsaid solid material from said centrifuge unit.
 24. The method of claim21 wherein said separating of said solvent from said hydrocarboncontaminant composition in said first fraction comprises the stepsof:providing a fractional distillation unit; introducing said firstfraction into said fractional distillation unit; heating said firstfraction in said fractional distillation unit in an amount sufficient tofractionally distill said first fraction and separate said solvent fromsaid hydrocarbon contaminant composition; and removing said solvent andsaid hydrocarbon contaminant composition from said fractionaldistillation unit.
 25. A method for removing hydrocarbon contaminantsfrom solid materials comprising the steps of:providing a treatmentsystem comprising a containment vessel and a washing chamber, saidwashing chamber comprising a first section comprising at least oneprimary screen member therein and a second section comprising at leastone secondary screen member therein, said second section of said washingchamber being positioned downstream from said first section, saidcontainment vessel further comprising a supply of solid materialtherein, said solid material being combined with at least onehydrocarbon contaminant composition; providing a supply of a solventdesigned to remove said hydrocarbon contaminant composition from saidsolid material, said solvent comprising at least one terpenecomposition; combining said solid material in said containment vesselwith said solvent in order to form a mixture; placing said mixture onsaid primary screen member in said first section of said washingchamber; applying a supply of washing water to said mixture on saidprimary screen member, said applying of said washing water to saidmixture producing a drainage product which passes through said primaryscreen member and a purified solid product which remains on said primaryscreen member and does not pass therethrough, said drainage productcomprising said washing water, said solvent with said hydrocarboncontaminant composition dissolved therein, and finely-divided portionsof said solid material small enough to pass through said primary screenmember, with said purified solid product comprising remaining portionsof said solid material large enough to prevent passage thereof throughsaid primary screen member; transferring said purified solid product tosaid secondary screen member in said second section of said washingchamber; applying a supply of rinse water to said purified solid producton said secondary screen member, said rinse water passing through saidsecondary screen member; transferring said rinse water to said firstsection of said washing chamber after passage of said rinse waterthrough said secondary screen member, said rinse water thereafter beingused in said first section of said washing chamber to wash anyadditional amounts of solid material which enter said treatment system;removing said purified solid product from said treatment system aftersaid applying of said rinse water thereto, said purified solid producthaving said hydrocarbon contaminant composition removed therefrom;separating said drainage product into a first fraction and a secondfraction, said first fraction comprising said solvent with saidhydrocarbon contaminant composition dissolved therein, and said secondfraction comprising said washing water and said finely-divided portionsof said solid material which passed through said primary screen member;separating said washing water from said finely-divided portions of saidsolid material in said second fraction so that said washing water isrecovered from said second fraction in order to generate a supply ofrecycled water; separating said solvent from said hydrocarboncontaminant composition in said first fraction so that said solvent isrecovered from said first fraction in order to generate a supply ofrecovered solvent; supplying said containment vessel with said supply ofrecovered solvent in order to treat said additional amounts of solidmaterial which enter said treatment system; and supplying said secondsection of said washing chamber with said supply of recycled water inorder to rinse said additional amounts of solid material which entersaid treatment system.
 26. The method of claim 25 wherein saidseparating of said drainage product into said first fraction and saidsecond fraction comprises the steps of:providing a cyclonic separatorunit; introducing said drainage product into said cyclonic separatorunit at a fluid pressure sufficient to cause said drainage product tobegin rapidly swirling therein, said swirling of said drainage productcausing said drainage product to separate into said first fraction andsaid second fraction; and removing said first fraction and said secondfraction from said cyclonic separator unit.
 27. A method for removinghydrocarbon contaminants from solid materials comprising the stepsof:providing a supply of solid material combined with at least onehydrocarbon contaminant composition; providing a supply of a solventdesigned to remove said hydrocarbon contaminant composition from saidsolid material, said solvent comprising at least one terpenecomposition; combining said solid material with said solvent in order toform a mixture; applying a supply of water to said mixture so that saidwater passes therethrough in order to produce a drainage product and apurified solid product separate from said drainage product, saiddrainage product comprising said water, said solvent with saidhydrocarbon contaminant composition dissolved therein, andfinely-divided portions of said solid material; separating said drainageproduct into a first fraction and a second fraction, said first fractioncomprising said solvent with said hydrocarbon contaminant compositiondissolved therein, and said second fraction comprising said water andsaid finely-divided portions of said solid material; separating saidfirst fraction into a third fraction and a fourth faction, said thirdfraction comprising said solvent with said hydrocarbon contaminantcomposition dissolved therein, and said fourth fraction comprising anyresidual water and residual solid material which remained in said firstfraction after said separating of said drainage product into said firstfraction and said second fraction; combining said second fraction andsaid fourth fraction to form a sludge product; separating said sludgeproduct into a fifth fraction and a sixth fraction, said fifth fractioncomprising said water from said second fraction and said residual waterfrom said fourth fraction which combine to produce a supply of recycledwater, with said sixth fraction comprising said finely-divided portionsof said solid material from said second fraction and said residual solidmaterial from said fourth fraction; separating said third fraction intoa seventh fraction and an eighth fraction, said seventh fractioncomprising a supply of recovered solvent, and said eighth fractioncomprising said hydrocarbon contaminant composition; collecting saidsupply of recovered solvent in order to subsequently treat anyadditional amounts of contaminated solid material; and collecting saidsupply of recycled water so that said recycled water may be applied tosaid additional amounts of contaminated solid material.
 28. The methodof claim 27 wherein said separating of said drainage product into saidfirst fraction and said second fraction comprises the steps of:providinga primary cyclonic separator unit; introducing said drainage productinto primary cyclonic separator unit at a fluid pressure sufficient tocause said drainage product to begin rapidly swirling therein, saidswirling of said drainage product causing said drainage product toseparate into said first fraction and said second fraction; and removingsaid first fraction and said second fraction from said primary cyclonicseparator unit; andsaid separating of said first fraction into saidthird fraction and said fourth fraction comprises the steps of:providing a secondary cyclonic separator unit in fluid communicationwith and downstream from said primary cyclonic separator unit;introducing said first fraction into said secondary cyclonic separatorunit at a fluid pressure sufficient to cause said first fraction tobegin rapidly swirling therein, said swirling of said first fractioncausing said first fraction to separate into said third fraction andsaid fourth fraction; and removing said third fraction and said fourthfraction from said secondary cyclonic separator unit.
 29. A method forremoving hydrocarbon contaminants from solid materials comprising thesteps of:providing a treatment system comprising a containment vesseland a washing chamber, said washing chamber comprising a first sectioncomprising at least one primary screen member therein and a secondsection comprising at least one secondary screen member therein, saidsecond section of said washing chamber being positioned downstream fromsaid first section, said containment vessel further comprising a supplyof solid material therein, said solid material being combined with atleast one hydrocarbon contaminant composition; providing a supply of asolvent designed to remove said hydrocarbon contaminant composition fromsaid solid material, said solvent comprising at least one terpenecomposition; combining said solid material in said containment vesselwith said solvent in order to form a mixture; placing said mixture onsaid primary screen member in said first section of said washingchamber; applying a supply of washing water to said mixture on saidprimary screen member, said applying of said washing water to saidmixture producing a drainage product which passes through said primaryscreen member and a purified solid product which remains on said primaryscreen member and does not pass therethrough, said drainage productcomprising said washing water, said solvent with said hydrocarboncontaminant composition dissolved therein, and finely-divided portionsof said solid material small enough to pass through said primary screenmember, with said purified solid product comprising remaining portionsof said solid material large enough to prevent passage thereof throughsaid primary screen member; transferring said purified solid product tosaid secondary screen member in said second section of said washingchamber; applying a supply of rinse water to said purified solid producton said secondary screen member, said rinse water passing through saidsecondary screen member; transferring said rinse water to said firstsection of said washing chamber after passage of said rinse waterthrough said secondary screen member, said rinse water thereafter beingused in said first section of said washing chamber to wash anyadditional amounts of solid material which enter said treatment system;removing said purified solid product from said treatment system aftersaid applying of said rinse water thereto, said purified solid producthaving said hydrocarbon contaminant composition removed therefrom;providing a primary cyclonic separator unit in fluid communication withsaid treatment system; introducing said drainage product into saidprimary cyclonic separator unit at a fluid pressure sufficient to causesaid drainage product to begin rapidly swirling therein, said swirlingof said drainage product causing said drainage product to separate intoa first fraction and a second fraction, said first fraction comprisingsaid solvent with said hydrocarbon contaminant composition dissolvedtherein, and said second fraction comprising said washing water and saidfinely-divided portions of said solid material which passed through saidprimary screen member; removing said first fraction and said secondfraction from said primary cyclonic separator unit; providing asecondary cyclonic separator unit in fluid communication with anddownstream from said primary cyclonic separator unit; introducing saidfirst fraction into said secondary cyclonic separator unit at a fluidpressure sufficient to cause said first fraction to begin rapidlyswirling therein, said swirling of said first fraction causing saidfirst fraction to separate into a third fraction and a fourth fraction,said third fraction comprising said solvent with said hydrocarboncontaminant composition dissolved therein, and said fourth fractioncomprising any residual water and residual solid material which remainedin said first fraction after said separating of said drainage productinto said first fraction and said second fraction; removing said thirdfraction and said fourth fraction from said secondary cyclonic separatorunit; combining said second fraction and said fourth fraction to form asludge product; providing a centrifuge unit in fluid communication withsaid primary cyclonic separator unit and said secondary cyclonicseparator unit; introducing said sludge product into said centrifugeunit; rotating said sludge product within said centrifuge unit at arotational speed sufficient to separate said sludge product into a fifthfraction and a sixth fraction, said fifth fraction comprising saidwashing water from said second fraction and said residual water fromsaid fourth fraction which combine to produce a supply of recycledwater, with said sixth fraction comprising said finely-divided portionsof said solid material from said second fraction and said residual solidmaterial from said fourth fraction; removing said fifth fraction andsaid sixth fraction from said centrifuge unit; providing a fractionaldistillation unit in fluid communication with said secondary cyclonicseparator unit; introducing said third fraction into said fractionaldistillation unit; heating said third fraction in said fractionaldistillation unit in an amount sufficient to fractionally distill saidthird fraction and generate a seventh fraction and an eighth fractionfrom said third fraction, said seventh fraction comprising a supply ofrecovered solvent, and said eighth fraction comprising said hydrocarboncontaminant composition; removing said seventh fraction and said eighthfraction from said fractional distillation unit; supplying saidcontainment vessel with said supply of recovered solvent in order totreat said additional amounts of solid material which enter saidtreatment system; and transferring said supply of recycled water to saidsecond section of said washing chamber, said recycled water thereafterbeing used in said second section of said washing chamber as said rinsewater in order to rinse said additional amounts of solid material whichenter said treatment system.